Display Device and Luminance Control Method Thereof and Mobile Terminal Using the Same

ABSTRACT

The present disclosure relates to a display device, a luminance control method thereof, and a mobile terminal using the same. The display device includes a display panel in which a pixel array including at least a first pixel region and a second pixel region are disposed; a touch sensor disposed on the pixel array; a display panel driver configured to write pixel data of an input image to pixels in the first pixel region and the second pixel region; a touch sensor driver configured to drive the touch sensor and detect a touch input on the pixel array to generate touch coordinate data; and a luminance control device configured to lower the luminance of one of the first and second pixel regions in at least some gray scales when the touch input is detected on the pixel array.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.17/371,803 filed on Jul. 9, 2021 which claims priority to and thebenefit of Republic of Korea Patent Application No. 10-2020-0102139,filed Aug. 14, 2020, each of which is hereby incorporated by referencein its entirety.

BACKGROUND 1. Field

The present disclosure relates to a display device capable ofcontrolling luminance of a screen for each region, a luminance controlmethod thereof, and a mobile terminal using the same.

2. Discussion of Related Art

An electroluminescent display device is roughly classified into aninorganic light emitting display device and an organic light emittingdisplay device depending on the material of a light emitting layer. Theorganic light emitting display device of an active matrix type includesan organic light emitting diode (hereinafter referred to as “OLED”) thatemits light by itself (e.g., self-luminescent), and has an advantagethat the response speed is fast, and the luminous efficiency, luminousand viewing angle are large. In the organic light emitting displaydevice, an organic light emitting diode (OLED) is formed on each of thepixels. The organic light emitting display device has a high responsespeed, excellent luminous efficiency, luminous, viewing angle, and thelike, and is capable of expressing black gradation in complete black,thereby providing excellent contrast ratio and color reproduction.

The multimedia capabilities of mobile terminals are improving. Forexample, a camera may be built into a smart phone, and the resolution ofthe camera is increasing to the level of a conventional digital camera.However, the front camera of a smart phone restricts the screen design,making it difficult to design the screen. In order to reduce the spaceoccupied by the camera, a screen design including a notch or a punchhole has been adopted in smartphones, but the screen size is stilllimited due to the camera, and a full-screen display could have not beenimplemented.

SUMMARY

In order to implement a full-screen display, a sensing region in whichlow-resolution pixels may be disposed within a screen of a display panelmay be provided. Since the number of pixels lighted in such a sensingregion is relatively small, the uniformity of luminance of the entirescreen may be driven by a relatively high voltage to the pixels in thesensing region. In this case, the deterioration of the pixels in thesensing region is accelerated compared to the pixels in thehigh-resolution region, so that the lifetime of the pixels may beshortened. In addition, power consumption may be different for eachregion of the screen, and a difference in power consumption may occurfor each channel of the data driver.

The present disclosure provides a display device capable of implementinga full-screen display and improving the lifetime and power consumptionof pixels, a luminance control method thereof, and a mobile terminalusing the same.

It should be noted that objects of the present disclosure are notlimited to the above-described objects, and other objects of the presentdisclosure will be apparent to those skilled in the art from thefollowing descriptions.

According to an embodiment of the present disclosure, a display devicemay include: a display panel on which a pixel array including at least afirst pixel region and a second pixel region are disposed; a touchsensor disposed on the pixel array; a display panel driver configured towrite pixel data of an input image to pixels in the first pixel regionand the second pixel region; a touch sensor driver configured to drivethe touch sensor and detect a touch input on the pixel array to generatetouch coordinate data; and a luminance control device configured tolower the luminance of one of the first and second pixel regions in atleast some gray scales when the touch input is detected on the pixelarray.

According to an embodiment of the present disclosure, a method forcontrolling luminance of a display device may include: writing pixeldata of an input image to pixels in the first pixel region and thesecond pixel region; driving the touch sensor and detecting a touchinput on the pixel array to generate touch coordinate data; and loweringthe luminance of one of the first and second pixel regions when thetouch input is detected on the pixel array.

According to an embodiment of the present disclosure, a mobile terminalmay include the display device; a sensor configured to sense changes inmovement and inclination in real time; a host system connected to thesensor and configured to transmit pixel data of an input image to thedisplay panel driver, and to receive the touch coordinate data from thetouch sensor driver; and a luminance control device configured to lowerthe luminance of one of the first and second pixel regions in at leastsome gray scales when the touch input is detected on the pixel array.

According to the present disclosure, since a sensor is disposed on ascreen on which an image is displayed, a screen of a full-screen displaymay be implemented.

According to the present disclosure, it is possible to improve thelifetime of pixels in a low Pixels Per Inch (PPI) region in which asensor is disposed and power consumption of a display device withoutdeteriorating luminance felt by the user.

Effects of the present disclosure are not limited to the above-describedeffects, and other effects which are not mentioned can be apparentlyunderstood by those skilled in the art from a disclosure of claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the presentdisclosure will become more apparent to those of ordinary skill in theart by describing exemplary embodiments thereof in detail with referenceto the attached drawings, in which:

FIG. 1 is a schematic cross-sectional view of a display panel accordingto an embodiment of the present disclosure;

FIG. 2 is a plan view showing a part of a screen including a sensingregion on a display panel according to an embodiment of the presentdisclosure;

FIG. 3 is a diagram illustrating an example of a pixel arrangement in adisplay region according to an embodiment of the present disclosure;

FIG. 4 is a diagram illustrating a pixel and a light transmitting partof an imaging region according to an embodiment of the presentdisclosure;

FIG. 5 is a block diagram schematically showing a mobile terminalaccording to an embodiment of the present disclosure;

FIG. 6 is a block diagram showing a display panel and a display paneldriver according to an embodiment of the present disclosure;

FIG. 7 is a block diagram schematically showing the configuration of adrive IC according to one embodiment;

FIG. 8 is a circuit diagram showing an example of a pixel circuitaccording to one embodiment;

FIG. 9 is a diagram illustrating a method of driving the pixel circuitshown in FIG. 8 according to one embodiment;

FIGS. 10 and 11 are views showing signal paths between a drive IC fordriving a pixel, a touch IC for driving a touch sensor, and a hostsystem in a mobile terminal according to an embodiment of the presentdisclosure;

FIG. 12 is a diagram showing a luminance control device using digitalgamma compensation technology according to one embodiment;

FIG. 13 is a diagram showing a luminance control device using an analoggamma compensation technology according to one embodiment;

FIG. 14 is a diagram showing a gamma curve in which luminance is equallydefined in all regions of a screen according to one embodiment;

FIGS. 15 to 17 are diagrams showing gamma curves in which luminance of ascreen is defined differently for each region according to oneembodiment;

FIG. 18 is a flowchart illustrating a method of controlling luminance ofa display device according to a first embodiment of the presentdisclosure;

FIG. 19 is a flowchart illustrating a method of controlling luminance ofa display device according to a second embodiment of the presentdisclosure;

FIG. 20 is a diagram illustrating an example in which a touch input isgenerated in a second pixel region in a mobile terminal according to oneembodiment;

FIG. 21 is a flowchart illustrating a method of controlling luminance ofa display device according to a third embodiment of the presentdisclosure;

FIG. 22 is a diagram illustrating an example in which a mobile terminalis rotated in a horizontal direction according to one embodiment;

FIG. 23 is a diagram illustrating an example in which a mobile terminalis rotated in a vertical reversal according to one embodiment;

FIG. 24 is a flowchart illustrating a method of controlling luminance ofa display device according to a fourth embodiment of the presentdisclosure; and

FIGS. 25A, 25B, and 25C are diagrams illustrating an example ofhistograms showing gray scale characteristics of an input image.

DETAILED DESCRIPTION

The advantages and features of the present disclosure and methods foraccomplishing the same will be more clearly understood from embodimentsdescribed below with reference to the accompanying drawings. However,the present disclosure is not limited to the following embodiments butmay be implemented in various different forms. Rather, the presentembodiments will make the disclosure of the present disclosure completeand allow those skilled in the art to completely comprehend the scope ofthe present disclosure. The present disclosure is only defined withinthe scope of the accompanying claims.

The shapes, sizes, ratios, angles, numbers, and the like illustrated inthe accompanying drawings for describing the embodiments of the presentdisclosure are merely examples, and the present disclosure is notlimited thereto. Like reference numerals generally denote like elementsthroughout the present specification. Further, in describing the presentdisclosure, detailed descriptions of known related technologies may beomitted to avoid unnecessarily obscuring the subject matter of thepresent disclosure.

The terms such as “comprising,” “including,” “having,” and “comprising”used herein are generally intended to allow other components to be addedunless the terms are used with the term “only.” Any references tosingular may include plural unless expressly stated otherwise.

Components are interpreted to include an ordinary error range even ifnot expressly stated.

When the position relation between two components is described using theterms such as “on,” “above,” “below,” and “next,” one or more componentsmay be positioned between the two components unless the terms are usedwith the term “immediately” or “directly.”

The terms “first,” “second,” and the like may be used to distinguishcomponents from each other, but the functions or structures of thecomponents are not limited by ordinal numbers or component names infront of the components.

The same reference numerals refer to the same elements throughout thedescription.

The following embodiments can be partially or entirely bonded to orcombined with each other and can be linked and operated in technicallyvarious ways. The embodiments can be carried out independently of or inassociation with each other.

Hereinafter, various embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings.

Referring to FIGS. 1 and 2 , the display panel 100 includes a screen forreproducing an input image. The screen may be divided into first pixelregion DA and a second pixel region CA having different resolutions.

Each of the first pixel region DA and the second pixel region CAincludes a pixel array in which pixels to which pixel data of an inputimage is written are disposed. The second pixel region CA may be a lowerresolution pixel region than the first pixel region DA. The pixel arrayof the first pixel region DA may include pixels disposed with a highPixels Per Inch (PPI). The pixel array of the second pixel region CA mayinclude pixels disposed with a low PPI that is less than the high PPI.

As illustrated in FIG. 2 , one or more sensor modules SS1 and SS2 facingthe second pixel region CA may be disposed under the display panel 100.For example, various sensors such as an imaging module including animage sensor, an infrared sensor module, and an illuminance sensormodule may be disposed under the second pixel region CA of the displaypanel 100. The second pixel region CA may include a light transmittingpart to increase transmittance of light directed to the sensor module.

Since the first pixel region DA and the second pixel region CA includepixels, the input image may be displayed in the first pixel region DAand the second pixel region CA.

Each of the pixels in the first pixel region DA and the second pixelregion CA includes sub-pixels having different colors to implement animage color. The sub-pixels include red (Red, hereinafter referred to as“R sub-pixel”), green (Green, hereinafter referred to as “G sub-pixel”),and blue (blue, hereinafter referred to as “B sub-pixel”). Although notshown, each of the pixels P may further include a white sub-pixel(hereinafter referred to as “W sub-pixel”). Each of the sub-pixels mayinclude a pixel circuit driving a light emitting element.

An image quality compensation algorithm for compensating the luminanceand color coordinates of pixels in the second pixel region CA having alower PPI than the first pixel region CA may be applied.

In the display device of the present disclosure, since pixels aredisposed in the second pixel region CA where the sensor is disposed, thedisplay region of the screen is not limited due to an imaging modulesuch as a camera. Accordingly, the display device of the presentdisclosure may implement a screen of a full-screen display.

The display panel 100 has a width in the X-axis direction, a length inthe Y-axis direction, and a thickness in the Z-axis direction. Thedisplay panel 100 may include a circuit layer 12 disposed on a substrateand a light emitting element layer 14 disposed on the circuit layer 12.A polarizing plate 18 may be disposed on the light emitting elementlayer 14 and a cover glass 20 may be disposed on the polarizing plate18.

The circuit layer 12 may include a pixel circuit connected to wiringssuch as data lines, gate lines, and power supply lines, a gate driverconnected to the gate lines, and the like. The circuit layer 12 mayinclude transistors implemented as a thin film transistor (TFT) andcircuit elements such as a capacitor. The wiring and circuit elements ofthe circuit layer 12 may be implemented with a plurality of insulatinglayers, two or more metal layers separated with an insulating layertherebetween, and an active layer including a semiconductor material.

The light emitting element layer 14 may include a light emitting elementdriven by a pixel circuit. The light emitting element may be implementedas an OLED. The OLEDs include an organic compound layer formed betweenan anode and a cathode. The organic compound layer is a hole injectionlayer (HIL), a hole transport layer (HTL), an emission layer (EML), anelectron transport layer (ETL), and an electron injection layer (EIL)may be included, but is not limited thereto. When a voltage is appliedto the anode and cathode of the OLED, the holes passing through the holetransport layer (HTL) and the electrons passing through the electrontransport layer (ETL) move to the emission layer (EML) to form excitons,and visible light is emitted from the emission layer (EML). The lightemitting element layer 14 is disposed on pixels that selectivelytransmit red, green, and blue wavelengths, and may further include acolor filter array.

The light emitting element layer 14 may be covered by a protectivelayer, and the protective layer may be covered by an encapsulationlayer. The protective layer and the encapsulation layer may have astructure in which an organic film and an inorganic film are alternatelystacked. The inorganic film blocks or at least reduces the penetrationof moisture or oxygen. The organic film flattens the surface of theinorganic film. When the organic film and the inorganic film are stackedin multiple layers, the passage of moisture or oxygen is longer thanthat of a single layer, so that the penetration of moisture/oxygenaffecting the light emitting element layer 14 may be effectively blockedor at least reduced.

The polarizing plate 18 may be adhered to the encapsulation layer. Thepolarizing plate 18 improves outdoor visibility of the display device.The polarizing plate 18 reduces light reflected from the surface of thedisplay panel 100 and blocks light reflected from the metal of thecircuit layer 12 to improve brightness of pixels. The polarizing plate18 may be implemented as a linear polarizing plate and a polarizingplate or a circular polarizing plate in which a phase delay film isbonded.

FIG. 3 is a diagram showing an example of a pixel arrangement of a firstpixel region DA. FIG. 4 is a diagram showing an example of pixels and alight transmitting part of a second pixel region CA. In FIGS. 3 and 4 ,wirings connected to the pixels are omitted.

Referring to FIG. 3 , the first pixel region DA includes pixels PIX1 andPIX2 arranged with a high PPI. Each of the pixels PIX1 and PIX2 may beimplemented as a real type pixel in which R, G, and B sub-pixels ofthree primary colors are formed as one pixel. Each of the pixels PIX1and PIX2 may further include a W sub-pixel omitted from the drawing. Inaddition, two sub-pixels may be configured as one pixel by using asub-pixel rendering algorithm. For example, using a pixel renderingalgorithm, the first pixel PIX1 may be composed of R and G sub-pixels,and the second pixel PIX2 may be composed of B and G sub-pixels. Thepixel-rendering algorithm may compensate for an insufficient colorexpression in each of the pixels PIX1 and PIX2 with an average value ofcorresponding color data between neighboring pixels.

Referring to FIG. 4 , the second pixel region CA includes a pixel groupPG spaced apart by a predetermined distance and light transmitting partsAG disposed between neighboring pixel groups PG. The external light isreceived by the lens of the sensor module through light transmittingparts AG. The light transmitting parts AG may include transparent mediahaving high transmittance without metal such that light may be incidentwith minimal light loss. In other words, the light transmitting parts AGmay be made of transparent insulating materials without metal wiring orpixels. The PPI of the second pixel region CA becomes lower than that ofthe first pixel region DA due to the light transmitting parts AG.

The pixel group PG of the second pixel region CA may include one or twopixels. Each of the pixels of the pixel group may include two to foursub-pixels. For example, one pixel in the pixel group may include R, G,and B sub-pixels or may include two sub-pixels, and may further includeW sub-pixels. In the example of FIG. 3 , the first pixel PIX1 iscomposed of R and G sub-pixels, and the second pixel PIX2 is composed ofB and G sub-pixels, but is not limited thereto.

The shape of the light transmitting parts AG is illustrated in acircular shape in FIG. 3 , but is not limited thereto. For example, thelight transmitting parts AG may be designed in various shapes, such as acircle, an oval, and a polygon.

FIG. 5 is a block diagram schematically showing a mobile terminalaccording to an embodiment of the present disclosure.

Referring to FIG. 5 , the mobile terminal of the present disclosureincludes a host system 200 and a display device 1000.

The display device 1000 includes a display panel in which pixels P aredisposed on a screen, a display panel driver 50 for writing pixel dataof an input image to the pixels P, touch sensors TS disposed on thescreen of the display panel, a touch sensor driver 54 driving the touchsensors TS.

The display panel driver 50 may write pixel data to pixels using atiming controller, a data driver, and a gate driver.

The touch sensor driver 54 drives touch sensors disposed on the screenof the display panel, and outputs touch coordinate data, based on achange in capacity of the touch sensors. The touch coordinate data istransmitted to the host system 200 including location information ofeach touch input.

The host system 200 transmits pixel data of the input image to thedisplay panel driver 50 through a graphic processor. The host system 200executes a command or application associated with touch coordinate datainput from the touch sensor driver 54.

The host system 200 may be connected to the communication unit 210, thesensor unit 220, the AI processor 230, and the like. The communicationunit 210 may connect the host system 200 to a network such as theInternet by forming a wired/wireless communication link.

The sensor unit 220 may include various sensors required in a mobileterminal. For example, the sensor unit 220 may include an accelerationsensor and a gyro sensor to detect changes in movement and inclinationof the mobile terminal in real time. The host system may activateluminance control data when the mobile terminal is rotated horizontallyor inverted vertically in response to an output signal from the sensorunit 200.

The AI processor 220 provides data requested by the host system 200based on a result of learning a neural network using a preset AIlearning algorithm. The neural network may be designed to simulate ahuman brain structure on a computer, and may include a plurality ofnetwork nodes having weights simulating neurons of the human neuralnetwork. The plurality of network nodes may exchange data according totheir respective connection relationships such that neurons may simulatesynaptic activity of neurons that send and receive signals throughsynapses. The neural network may include a deep learning model developedfrom a neural network model.

The host system 200 or the touch sensor driver 54 may transmitregion-specific luminance control data including touch input informationof the second pixel region CA to the display panel driver 50. The hostsystem 200 may transmit, to the display panel driver, region-specificluminance control data indicating an application in which a touch inputfrequently occurs in the second pixel region CA of the screen based onthe learning result of the AI processor 220.

The display panel driver 50 may lower the luminance of one of the firstand second pixel regions when the touch input is detected on the pixelarray. For example, the display panel driver 50 lowers the luminance ofthe second pixel region CA when the second pixel region CA is frequentlytouched or a touch input of the second pixel region CA is expected inresponse to the region-specific luminance control data from the hostsystem 200 or the touch sensor driver 54. As a result, the display paneldriver 50 may extend the lifetime of the pixels in the second pixelregion CA and reduce power consumption of the display device withoutdeteriorating luminance felt by the user. When the touch input isfrequently generated in the second pixel region CA, the user does notsensitively feel a decrease in luminance of the pixels because thepixels of the second pixel region CA are covered by a finger or a pen.

The host system 200 may rotate image data in association with therotation direction of the mobile terminal when the mobile terminal isrotated horizontally or the position of the mobile terminal is invertedhorizontally or vertically, based on the output signal of the sensorunit 210. If the position of the mobile terminal is invertedhorizontally or vertically, the luminance of the second pixel region CAmay be lowered when pixel data of low image quality such as a homebutton or a fixed icon is written in the second pixel region CA.

FIG. 6 is a block diagram showing a display panel and a display paneldriver according to an embodiment of the present disclosure. FIG. 7 is ablock diagram schematically showing the configuration of a drive IC.

Referring to FIGS. 6 and 7 , a screen on which an input image isreproduced on the display panel 100 includes pixel arrays of first andsecond pixel regions DA and CA.

The pixel array of the display panel 100 includes pixels P arranged in amatrix form defined by data lines DL, gate lines GL intersected with thedata lines DL, and the data lines DL and the gate lines GL. The pixelarray may further include power supply wirings such as VDD line PL1,Vini line PL2, and VSS line PL3 shown in FIG. 8 .

The pixel array may be divided into a circuit layer 12 and a lightemitting element layer 18 as shown in FIG. 1 . Each of the pixels P mayinclude two to four sub-pixels as described above. Each of thesub-pixels includes a pixel circuit disposed on the circuit layer 12.The pixel circuit may include a driving element that supplies current tothe light emitting element, a plurality of switch elements that sample athreshold voltage of the driving element and switch a current path ofthe pixel circuit, a capacitor that maintains the gate voltage of thedriving element, and the like. The pixel circuit may be disposed underthe light emitting element.

Touch sensors may be disposed on the screen of the display panel. Thetouch sensors may be disposed on the screen of the display panel 100 inan On-cell type or an Add-on type, or an In-cell type touch sensor maybe built into a pixel array. In the case of the Add-on type, the touchsensors may be disposed above the light emitting element layer 18. Thetouch sensor may be implemented as a capacitive type touch sensor, forexample, a mutual capacitance sensor or a self-capacitance sensor. Theself-capacitance is formed along single-layer conductor wiring formed inone direction. The mutual capacitance is formed between two orthogonalconductor wirings.

The display panel 100 may be implemented as a flexible panel applicableto a flexible display. In the flexible panel, the size of the screen maybe varied and may be easily manufactured in various designs.

The display panel driver writes pixel data of the input image to thepixels P. The display panel driver includes a data driver 306 thatsupplies a data voltage of pixel data to the data lines DL, a gatedriver 120 that sequentially supplies a gate pulse to the gate lines GL,and a timing controller 303 that controls the data driver 306 and thegate driver 120. The data driver 306 and the timing controller 303 maybe integrated in the drive IC 300.

The touch sensor driver shown in FIG. 5 may be integrated in the touchIC 400 and connected to the drive IC 300 and the host system 200.

The touch IC 400 may include a sensing unit and a touch determinationunit. The sensing unit may supply driving signals to the touch sensorsthrough sensor lines omitted from the drawing to charge electric chargeinto the touch sensors, amplify and integrate the amount of the electriccharge of the touch sensors. In addition, the sensing unit may convertthe amount of the electric charge into digital data to sense the changein capacity before and after the touch input. To this end, the sensingunit includes an amplifier that amplifies the touch sensor signal, anintegrator that accumulates the output voltage of the amplifier, and ananalog-to-digital converter (hereinafter referred to as “ADC”) thatconverts the voltage of the integrator into digital data, etc. Thedigital data output from the ADC is touch raw data indicating the changein capacity of the touch sensor before and after the touch input. Thetouch determination unit compares the touch raw data input from thesensing unit with a preset threshold, detects data higher than thethreshold value, and generates touch coordinate data indicating theposition of the touch sensor of the detected data. The touchdetermination unit may transmit the touch coordinate data to the hostsystem 200 together with an identification code indicating each touchinput.

The touch IC 400 may transmit the region-specific luminance control dataindicating touch input information of the second pixel region CA to thedrive IC 300.

The drive IC 300 may be adhered to the display panel 100. The drive IC300 receives pixel data and timing signals of an input image from thehost system 200, supplies a data voltage of the pixel data to thepixels, and synchronizes the data driver 306 and the gate driver 120.

The drive IC 300 is connected to the data lines DL through data outputchannels to supply a data voltage of pixel data to the data lines DL.The drive IC 300 may output a gate-timing signal for controlling thegate driver 120 through gate timing signal output channels. The gatetiming signal generated from the timing controller 303 may include astart pulse (Gate start pulse, VST), a shift clock (Gate shift clock,CLK), and the like. The start pulse VST and the shift clock CLK swingbetween the gate-on voltage VGL and the gate-off voltage VGH. The gatetiming signals VST and CLK output from the level shifter 307 are appliedto the gate driver 120 to control the shift operation of the gate driver120.

The gate driver 120 may include a shift register formed on a circuitlayer of the display panel 100 together with a pixel array. The shiftregister of the gate driver 120 sequentially supplies gate signals tothe gate lines GL under the control of the timing controller 303. Thegate signal may include a scan pulse and an EM pulse of a light emittingsignal. The shift register may include a scan driver outputting scanpulses and an EM driver outputting EM pulses. In FIG. 7 , GVST and GCLKare gate-timing signals input to the scan driver. EVST and ECLK aregate-timing signals input to the EM driver.

The drive IC 300 may be connected to the host system 200, a first memory301, and the display panel 100. The drive IC 300 may include a datacalculating unit 308, a timing controller 303, a data driver 306, agamma compensation voltage generating unit 305, a power supply unit 304,a second memory 302, and the like.

The data-calculating unit 308 includes a receiving unit that receivespixel data input as a digital signal from the host system 200 and a dataprocessor that processes pixel data input through the receiving unit toimprove image quality. The data processor may include a data-restoringunit that decodes and restores compressed pixel data, an opticalcompensation unit that adds a preset optical compensation value to thepixel data, and the like. The optical compensation value may be set as avalue for correcting luminance of each pixel data based on luminance ofa screen measured based on a camera image captured in a manufacturingprocess.

The timing controller 303 provides pixel data of an input image receivedfrom the host system 200 to the data driver 306. The timing controller303 generates a gate-timing signal for controlling the gate driver 120and a source-timing signal for controlling the data driver 306 tocontrol the operation timing of the gate driver 120 and the data driver306 and synchronizes the gate driver 120 and the data driver 306.

The data driver 306 converts digital data including pixel data receivedfrom the timing controller 303 through a digital to analog converter(hereinafter referred to as “DAC”) into a gamma compensation voltage tooutput the data voltage. The data voltage output from the data driver306 is supplied to the data lines DL of the pixel array through anoutput buffer connected to the data channel of the drive IC 300.

The gamma compensation voltage-generating unit 305 may divide gammareference voltage from the power supply unit 304 through a dividercircuit to generate a gamma compensation voltage for each gray scale.The gamma compensation voltage is an analog voltage whose voltage is setfor each gray scale of pixel data. The gamma compensation voltage outputfrom the gamma compensation voltage-generating unit 305 is provided tothe data driver 306.

The power supply unit 304 generates power required for driving the pixelarray of the display panel 100, the gate driver 120, and the drive IC300 using a DC-DC converter. The DC-DC converter may include a chargepump, a regulator, a buck converter, a boost converter, and the like.The power supply unit 304 may adjust a DC input voltage from the hostsystem 200 to generate provide a direct current power such as a gammareference voltage, a gate-on voltage VGL, a gate-off voltage VGH, apixel driving voltage VDD, a low-potential power supply voltage VSS, andan initialization voltage Vini. The gamma reference voltage is suppliedto the gamma compensation voltage-generating unit 305. The gate-onvoltage VGL and the gate-off voltage VGH are supplied to the levelshifter 307 and the gate driver 120. The pixel power, such as the pixeldriving voltage VDD, the low-potential power supply voltage VSS, and theinitialization voltage Vini, is commonly supplied to the pixels P. Theinitialization voltage Vini is set to a DC voltage lower than the pixeldriving voltage VDD and lower than the threshold voltage of the lightemitting element OLED, so that the main nodes of the pixel circuits areinitialized, and the light emission of the light emitting element OLEDis suppressed.

The second memory 302 stores a compensation value, register settingdata, and the like received from the first memory 301 when the power isinput to the drive IC 300. The compensation value may be applied tovarious algorithms for improving the image quality. The compensationvalue may include an optical compensation value. The register settingdata defines the operations of the data driver 306, the timingcontroller 303, the gamma compensation voltage-generating unit 305, andthe like. The first memory 301 may include a flash memory. The secondmemory 302 may include static RAM (SRAM).

The host system 200 may be implemented as an application processor (AP).The host system 200 may transmit pixel data of an input image to thedrive IC 300 through a video data interface such as a mobile industryprocessor interface (MIPI), a V-by-one, and a display port (DP). Thehost system 200 may be connected to the drive IC 300 through a flexibleprinted circuit (FPC), for example, a flexible printed circuit (FPC)201. The touch IC 400 may be mounted on the FPC 201, but is not limitedthereto.

The host system 200 or the touch IC 400 may transmit the region-specificluminance control data including touch input information of the secondpixel region CA to the drive IC 300. In an image where a touch input isoccurred frequently in the second pixel region CA or a touch input isexpected to occur frequently in the second pixel region CA in responseto the region-specific luminance control data, the drive IC 300 maycontrol the luminance of the second pixel region CA to be lower thanotherwise. In addition, in an image in which a touch input does notoccur frequently or there is little touch input on the second pixelregion CA, the drive IC 300 may vary the luminance reduction widthaccording to the gray scale of the pixel data in order to extend thelifetime of the pixels while reducing image quality degradation.

The pixel circuit and the gate driver 120 may include a plurality oftransistors. The transistors may be implemented as an oxide thin filmtransistor (TFT) including an oxide semiconductor, an LTPS TFT includinga low temperature poly silicon (LTPS), or the like. Each of thetransistors may be implemented as a p-channel TFT or an n-channel TFT.In the embodiment, an example in which the transistors of the pixelcircuit are implemented as p-channel TFTs will be mainly described, butthe present disclosure is not limited thereto.

The transistor is a three-electrode element including a gate, a source,and a drain. The source is an electrode that supplies a carrier to thetransistor. In the transistor, the carrier starts flowing from thesource. The drain is an electrode through which the carrier exits fromthe transistor. In the transistor, the flow of the carrier flows fromthe source to the drain. In the case of an n-channel transistor, sincethe carriers are electrons, the source voltage has a voltage lower thanthe drain voltage such that electrons may flow from the source to thedrain. In the n-channel transistor, the direction of current is flowedfrom the drain to the source. In the case of the p-channel transistorPMOS, since the carriers are holes, the source voltage is higher thanthe drain voltage such that the holes may flow from the source to thedrain. In the p-channel transistor, since the holes flow from the sourceto the drain, the current flows from the source to the drain. It shouldbe noted that the source and drain of the transistor are not fixed. Forexample, the source and drain may be changed according to the appliedvoltage. Therefore, the present disclosure is not limited due to thesource and drain of the transistor. In the following description, thesource and drain of the transistor will be referred to as first andsecond electrodes.

The gate pulse swings between a gate on voltage and a gate off voltage.The gate-on voltage is set to a voltage higher than the thresholdvoltage of the transistor, and the gate-off voltage is set to a voltagelower than the threshold voltage of the transistor. The transistor isturned on in response to the gate-on voltage, while it is turned off inresponse to the gate-off voltage. In the case of an n-channeltransistor, the gate-on voltage may be a gate high voltage VGH, and thegate-off voltage may be a gate low voltage VGL. In the case of ap-channel transistor, the gate-on voltage may be the gate low voltageVGL, and the gate-off voltage may be the gate high voltage VGH.

The driving element of the pixel circuit may be implemented as atransistor. It is preferable that the driving element has uniformelectrical characteristics among all pixels, but due to processdeviation and element characteristic deviation, the electricalcharacteristics may differ between the pixels and may change over thelapse of display driving time. In order to compensate for deviations inelectrical characteristics of the driving element, the display devicemay include an internal compensation circuit and an externalcompensation circuit. The internal compensation circuit is added to thepixel circuit in each of the sub-pixels to sample the threshold voltageVth and/or the mobility (μ) of the driving element, which variesaccording to the electrical characteristics of the driving element, andcompensates the change in real time. The external compensation circuittransmits the threshold voltage and/or mobility of the driving elementsensed through a sensing line connected to each of the sub-pixels to anexternal compensation unit. The compensation unit of the externalcompensation circuit compensates for changes in electricalcharacteristics of the driving element by modulating pixel data of theinput image by reflecting the sensing result. The voltage of the pixelvaried according to the electrical characteristics of the drivingelement is sensed, the data of the input image is modulated in anexternal circuit based on the sensed voltage, thereby compensating forthe electrical characteristic deviation of the driving element betweenthe pixels.

FIG. 8 is a circuit diagram showing an example of a pixel circuit towhich an internal compensation circuit is applied according to oneembodiment. FIG. 9 is a diagram illustrating a method of driving thepixel circuit shown in FIG. 8 according to one embodiment. The pixelcircuits shown in FIGS. 8 and 9 may be applied equally to the pixelcircuits of the first pixel region DA and the second pixel region CA.The pixel circuit applicable to the present disclosure may beimplemented with the circuit shown in FIG. 8 , but is not limitedthereto.

Referring to FIGS. 8 and 9 , the pixel circuit may include a lightemitting element OLED, a driving element DT supplying current to thelight emitting element OLED, and an internal compensation circuit. Inthe internal compensation circuit, the threshold voltage Vth of thedriving element DT is sampled using a capacitor Cst and a plurality ofswitch elements M1 to M6 and the gate voltage of the driving element DTis compensated by the threshold voltage Vth of the driving element DT.Each of the driving element DT and the switch elements M1 to M6 may beimplemented as a p-channel TFT.

The driving period of the pixel circuit may be divided into aninitialization period Tini, a sampling period Tsam, and a light emissionperiod Tem as shown in FIG. 9 .

During the initialization period Tini, the N−1th scan signal SCAN(N−1)is generated with a pulse of the gate-on voltage VGL, and each voltageof the Nth scan signal SCAN(N) and the light emitting signal EM(N) is agate-off voltage VGH. During the sampling period Tsam, the Nth scansignal SCAN(N) is generated as a pulse of the gate-on voltage VGL, andeach voltage of the N−1th scan signal SCAN(N−1) and the light emittingsignal EM(N) is a gate-off voltage VGH. During at least a portion of thelight emission period Tem, the light emitting signal EM(N) is generatedas a gate-on voltage VGL, and each voltage of the N−1th scan signalSCAN(N−1) and the Nth scan signal SCAN(N) is the gate-off voltage VGH.

During the initialization period Tin, the fifth switch element M5 isturned on according to the gate-on voltage VGL of the N−1th scan signalSCAN(N−1) to initialize the pixel circuit. During the sampling periodTsam, the first and second switch elements M1 and M2 are turned onaccording to the gate-on voltage VGL of the N-th scan signal SCAN(N) sothat the data voltage of the pixel data Vdata is applied to the gate ofthe driving element DT. In this case, the threshold voltage of thedriving element DT is sampled, and the data voltage compensated by thethreshold voltage is stored in the capacitor Cst. During the samplingperiod Tsam, the sixth switch element M6 is turned on to lower thevoltage of the fourth node n4 to the initialization voltage Vini so thatthe light emission of the light emitting element OLED is suppressed.During the light emission period Tem, the third and fourth switchelements M3 and M4 are turned on so that light emitting element OLED isemitted. In order to accurately express the luminance of low gray scalewith the duty ratio of the light emitting signal EM(N), during the lightemission period Tem, the light emitting signal EM(N) may swing betweenthe gate-on low voltage (VGL) and the gate-off voltage (VGH) at apredetermined duty ratio so that the third and fourth switch elements M1and M2 may repeat on/off.

The light emitting element OLED may be implemented as an organic lightemitting diode or an inorganic light emitting diode. Hereinafter, anexample in which a light emitting element OLED is implemented as anorganic light emitting diode will be described.

The light emitting element OLED may include an organic compound layerformed between the anode and the cathode. The organic compound layer mayinclude, but is not limited to, a hole injection layer (HIL), a holetransport layer (HTL), an emission layer (EML), an electron transportlayer (ETL), and an electron injection layer (EIL). When a voltage isapplied to the anode and cathode electrodes of the OLED, holes that havepassed through the hole transport layer (HTL) and electrons that havepassed through the electron transport layer (ETL) are moved to theemission layer (EML), and excitons are formed, such that visible lightis emitted from the emission layer (EML).

The anode electrode of the light emitting element OLED is connected tothe fourth node n4 between the fourth and sixth switch elements M4 andM6. The fourth node n4 is connected to the anode of the light emittingelement OLED, the second electrode of the fourth switch element M4, andthe second electrode of the sixth switch element M6. The cathodeelectrode of the light emitting element OLED is connected to the VSSline PL3 to which the low potential power supply voltage VSS is applied.The light emitting element OLED emits light with a current Ids flowingaccording to the gate-source voltage Vgs of the driving element DT. Thecurrent path of the light emitting element OLED is switched by the thirdand fourth switch elements M3 and M4.

The capacitor Cst is connected between the VDD line PL1 and the firstnode n1. The data voltage Vdata compensated by the threshold voltage Vthof the driving element DT is charged in the capacitor Cst. Since thedata voltage Vdata in each of the sub-pixels is compensated by thethreshold voltage Vth of the driving element DT, deviation of thecharacteristics of the driving element DT is compensated for in thesub-pixels.

The first switch element M1 is turned on in response to the gate-onvoltage VGL of the Nth scan pulse SCAN(N) to connect the second node n2and the third node n3. The second node n2 is connected to the gateelectrode of the driving element DT, the first electrode of the storagecapacitor Cst, and the first electrode of the first switch element M1.The third node n3 is connected to the second electrode of the drivingelement DT, the second electrode of the first switch element M1, and thefirst electrode of the fourth switch element M4. The gate electrode ofthe first switch element M1 is connected to the first gate line GL1 toreceive the Nth scan pulse SCAN(N). The first electrode of the firstswitch element M1 is connected to the second node n2, and the secondelectrode of the first switch element M1 is connected to the third noden3.

The second switch element M2 is turned on in response to the gate-onvoltage VGL of the Nth scan pulse SCAN(N) to supply the data voltageVdata to the first node n1. The gate electrode of the second switchelement M2 is connected to the first gate line GL1 to receive the Nthscan pulse SCAN(N). The first electrode of the second switch element M2is connected to the first node n1. The second electrode of the secondswitch element M2 is connected to the data line DL to which the datavoltage Vdata is applied. The first node n1 is connected to the firstelectrode of the second switch element M2, the second electrode of thethird switch element M2, and the first electrode of the driving elementDT.

The third switch element M3 is turned on in response to the gate-onvoltage VGL of the light emitting signal EM(N) to connect the VDD linePL1 to the first node n1. The gate electrode of the third switch elementM3 is connected to the third gate line GL3 to receive the light emittingsignal EM(N). The first electrode of the third switch element M3 isconnected to the VDD line PL1. The second electrode of the third switchelement M3 is connected to the first node n1.

The fourth switch element M4 is turned on in response to the gate-onvoltage VGL of the light emitting signal EM(N) to connect the third noden3 to the anode of the light emitting element OLED. The gate electrodeof the fourth switch element M4 is connected to the third gate line GL3to receive a light emitting signal EM(N). The first electrode of thefourth switch element M4 is connected to the third node n3, and thesecond electrode is connected to the fourth node n4.

The fifth switch element M5 is turned on in response to the gate-onvoltage VGL of the N−1th scan pulse SCAN(N−1) to connect the second noden2 to the Vini line PL2. The gate electrode of the fifth switch elementM5 is connected to the second gate line GL2 to receive an N−1th scanpulse SCAN(N−1). The first electrode of the fifth switch element M5 isconnected to the second node n2, and the second electrode is connectedto the Vini line PL2.

The sixth switch element M6 is turned on in response to the gate-onvoltage VGL of the Nth scan pulse SCAN(N) to connect the Vini line PL2to the fourth node n4. The gate electrode of the sixth switch element M6is connected to the first gate line GL1 to receive the Nth scan pulseSCAN(N). The first electrode of the sixth switch element M6 is connectedto the Vini line PL2, and the second electrode is connected to thefourth node n4.

The driving element DT drives the light emitting element OLED bycontrolling the current Ids flowing through the light emitting elementOLED according to the gate-source voltage Vgs. The driving element DTincludes a gate connected to the second node n2, a first electrodeconnected to the first node n1, and a second electrode connected to thethird node n3.

During the initialization period Tini, as shown in FIG. 9 , the N−1thscan pulse SCAN(N−1) is generated as the gate-on voltage VGL. The Nthscan pulse SCAN(N) and the light emitting signal EM(N) maintain thegate-off voltage VGH during the initialization period Tini. Accordingly,the fifth switch element M5 is turned on during the initializationperiod Tini, so that the second and fourth nodes n2 and n4 areinitialized to Vini. A hold period Th may be set between theinitialization period Tini and the sampling period Tsam. In the holdperiod Th, the gate pulses SCAN(N−1), SCAN(N), and EM(N) maintain theirprevious state.

During the sampling period Tsam, the Nth scan pulse SCAN(N) is generatedas the gate-on voltage VGL. The pulse of the Nth scan pulse SCAN(N) issynchronized with the data voltage Vdata of the Nth pixel line. TheN−1th scan pulse SCAN(N−1) and the light emitting signal EM(N) maintainthe gate-off voltage VGH during the sampling period Tsam. Accordingly,the first and second switch elements M1 and M2 are turned on during thesampling period Tsam.

During the sampling period Tsam, the gate voltage DTG of the drivingelement DT is increased by the current flowing through the first andsecond switch elements M1 and M2. When the driving element DT is turnedoff, the gate node voltage DTG is Vdata−|Vth|. In this case, the voltageof the first node n is also Vdata−|Vth|. During the sampling periodTsam, the gate-source voltage Vgs of the driving element DT is|Vgs|=Vdata−(Vdata−|Vth|)=|Vth|.

During the light emission period Tem, a light emitting signal EM(N) maybe generated as the gate-on voltage VGL. During the light emissionperiod Tem, the light emitting signal EM(N) is turned on/off at apredetermined duty ratio in order to improve expressiveness of the lowgray scale, to swing between the gate-on voltage VGL and the gate-offvoltage VGH. Accordingly, the light emitting signal EM(N) may begenerated as the gate-on voltage VGL during at least a portion of thelight emission period Tem.

When the light emitting signal EM(N) is the gate-on voltage VGL, thecurrent flows through the driving element DT to the light emittingelement OLED, so that the light emitting element OLED may emit light.During the light emission period Tem, the N−1th and Nth scan pulsesSCAN(N−1) and SCAN(N) maintain the gate-off voltage VGH. During thelight emission period Tem, the third and fourth switch elements M3 andM4 are turned on when the light emitting signal EM is the gate-onvoltage VGL. The third and fourth switch elements M3 and M4 are turnedon so that a current flows through the light emitting element OLED. Inthis case, Vgs of the driving element DT is |Vgs|=VDD−(Vdata−|Vth|), andthe current flowing through the light emitting element OLED isK(VDD−Vdata)². K is a constant value determined by the charge mobility,parasitic capacitance, and channel capacity of the driving element DT.

FIGS. 10 and 11 are diagrams showing signal paths between a drive IC fordriving a pixel, a touch IC for driving a touch sensor, and a hostsystem in a mobile terminal according to an embodiment of the presentdisclosure.

Referring to FIG. 10 , the mobile terminal includes a first signal path101 connecting the host system 200 and the touch IC 400, and a secondsignal path 102 connecting the host system 200 and the drive IC 300, anda third signal path 103 connecting the touch IC 400 and the drive IC300.

The touch IC 400 transmits touch coordinate data T-DATA indicating thepositions of each of the touch inputs detected on the screen of thedisplay panel 100 through the first signal path 101 as a predeterminedtouch report rate (Hz) to the host system 200. The touch report rate isa frequency at which the touch coordinate data T-DATA is transmitted,and the faster the touch report rate, the faster the update speed of thetouch coordinates. The first signal path 101 may transmit data T-DATAthrough a communication standard such as I2C or serial peripheralinterface bus (SPI) through one or more wirings.

The host system 200 transmits pixel data of an input image to be writtento the pixels of the display panel 100 to the drive IC 300 through thesecond signal path 102. The second signal path 102 may transmit dataD-DATA in a display data communication standard such as a MIPI,V-by-one, or display port (DP) through one or more wirings.

The touch IC 400 may transmit the region-specific luminance control dataL-DATA to the drive IC 300 through the third signal path 103. To thisend, a General Purpose Input/Output (GPIO) pin to which the wiring ofthe third signal path 103 is connected may be added to the drive IC 300.

The luminance control data L-DATA may include touch coordinate data ofthe second pixel region CA. In addition, the luminance control dataL-DATA may include touch input frequency data of the second pixel regionCA. The frequency data is an accumulated value of the number of touchinputs within the reference time counted in the preset reference timeunit in the second pixel region CA.

The touch IC 400 may transmit the luminance control data L-DATAincluding touch coordinate data and touch frequency data of the secondpixel region CA to the drive IC 300. The drive IC 300 may compare thetouch frequency data of the second pixel region CA with a presetthreshold in response to the luminance control data L-DATGA receivedfrom the touch IC 400. Accordingly, the luminance of the second pixelregion CA may be lowered when the number of touch inputs of the secondpixel region CA is greater than or equal to the threshold value withinthe reference time. In this case, since the second pixel region CA is asecond pixel region, the luminance of the second pixel region CA may belowered even if the gray scale value of the pixel data to be written tothe pixels of the second pixel region CA is not lowered. Since thesecond pixel region CA is a second pixel region, the luminance of thesecond pixel region CA may be lowered even if the data voltage of thepixel data to be written to the pixels of the second pixel region CA isnot lowered. Meanwhile, in order to lower the luminance of the secondpixel region CA, the pixel data to be written in the pixels of thesecond pixel region CA may be lowered to a value defined by a presetgamma curve (digital gamma correction). Alternatively, the data voltageVdata to be applied to the pixels of the second pixel region CA may belowered (analog gamma correction).

The reference time may be set to 1 second, and the threshold value maybe 3 to 5, but is not limited thereto. Assuming 60 frames per second,the threshold at which the luminance of the second pixel region CA isadjusted to be low may be 0.05 to 0.08 times per frame. In this case,the drive IC 300 may lower the luminance of the second pixel region CAwhen the touch frequency of the second pixel region CA is 3 to 5 timesor more per second.

The drive IC 300 may have the same luminance of the first and secondpixel regions CA when the number of touch inputs to the second pixelregion CA is less than the threshold value within the reference time. Inthis case, since the second pixel region CA is a second pixel region,the gray scale value of the pixel data to be written to the pixels ofthe second pixel region CA may be increased, or the data voltage Vdatato be applied to the pixels of the second pixel region CA may beincreased.

In another embodiment, when the number of touch inputs of the secondpixel region CA is less than a threshold value or no touch input is madewithin the reference time, the drive IC 300 may lower the luminance of aspecific gray scale or greater in the second pixel region CA, in orderto reduce a difference in image quality perceived by a user and reducethe lifetime of pixels, considering the gray scale characteristics ofthe image displayed in the second pixel region CA. In this case, sincethe second pixel region CA is a second pixel region, the drive IC 300increases the gray scale value of the pixel data to be written to thepixels of the second pixel region CA or increases the data voltage Vdatato be applied to the pixels of the second pixel region CA in a grayscale range less than the specific gray scale. On the other hand, inorder to lower the luminance of the second pixel region CA in a grayscale range equal to or greater than a specific gray scale, the drive IC300 does not modulate the gray scale value of the pixel data to bewritten to the pixels or may lower the gray scale value of the pixeldata. In addition, in order to lower the luminance of the second pixelregion CA in a gray scale range equal to or greater than a specific grayscale, the drive IC 300 may output the data voltage Vdata to be appliedto the pixels of the second pixel region CA as the same voltage as thefirst pixel region DA at the same gray scale, or may lower to thevoltage corresponding to the luminance defined by the gamma curve.

The specific gray scale may be varied based on a result of analyzingpixel data to be written in pixels of the second pixel region CA in theinput image. For example, the drive IC 300 may analyze the gray scaledistribution of the second pixel region CA for each frame period andselect a gray scale value representing the gray scale characteristics ofthe frame data. The drive IC 300 may store frame data in a memory usinga histogram analysis method, and accumulate pixel data for each grayscale from the frame data, such thin the gray scale value with thelargest accumulated value, that is, the gray scale value of the maximumfrequency may be selected as a specific gray scale.

In another embodiment, the touch IC 400 may compare the touch frequencydata of the second pixel region CA with a preset threshold. If thenumber of touch inputs of the second pixel region CA within a referencetime is greater than or equal to the threshold value, theregion-specific luminance control data L-DATA having an activation codevalue for lowering luminance of the second pixel region CA may betransmitted to the drive IC 300. The drive IC 300 may lower theluminance of the second pixel region CA in response to the luminancecontrol data L-DATGA having an activation code value.

The touch IC 400 may transmit the region-specific luminance control dataL-DATA having a deactivation code value to the drive IC 300 when thenumber of touch inputs of the second pixel region CA within thereference time is less than the threshold value. The drive IC 300 mayequalize the luminance of the first and second pixel regions CA inresponse to the luminance control data L-DATGA having a deactivationcode value.

In another embodiment, the drive IC 300 may lower luminance of aspecific gray scale or greater in the second pixel region CA in order toreduce a difference in image quality perceived by a user and reduce thelifetime of pixels in response to the luminance control data L-DATGAhaving a deactivation code value.

The region-specific luminance control data L-DATA may be transmitted tothe drive IC 300 through the third signal path 103. To this end, ageneral purpose input/output (GPIO) pin to which the wiring of the thirdsignal path 103 is connected may be added to the drive IC 300.

Referring to FIG. 11 , the mobile terminal includes a first signal path101 connecting the host system 200 and the touch IC 400, and the secondand third signal paths 102 and 104 connecting the host system 200 andthe drive IC 300.

The touch IC 400 transmits touch coordinate data T-DATA indicating thepositions of each of the touch inputs detected on the screen of thedisplay panel 100 through the first signal path 101 as a predeterminedtouch report rate (Hz) to the host system 200. The host system 200transmits pixel data of an input image to be written to the pixels ofthe display panel 100 to the drive IC 300 through the second signal path102.

The host system 200 may transmit the region-specific luminance controldata L-DATA to the drive IC 300 through the third signal path 104. Tothis end, the GPIO pin to which the wiring of the third signal path 104is connected may be added to the drive IC 300.

The host system 200 may count the touch coordinate data received fromthe touch IC 400 in a preset reference time unit and generate theaccumulated touch frequency within the reference time every referencetime. The host system 200 may transmit the region-specific luminancecontrol data L-DATA to the drive IC 300. The luminance control dataL-DATA may include touch coordinate data of the second pixel region CA.In addition, the luminance control data L-DATA may include touch inputfrequency data of the second pixel region CA. The frequency data is anaccumulated value of the number of touch inputs counted within thepreset reference time in the second pixel region CA. The drive IC 300may compare the touch frequency data of the second pixel region CA witha preset threshold in response to the luminance control data L-DATGAreceived from the touch IC 400. In addition, the drive IC 300 may lowerthe luminance of the second pixel region CA when the number of touchinputs to the second pixel region CA is greater than or equal to thethreshold value within the reference time.

The drive IC 300 may have the same luminance of the first and secondpixel regions CA when the number of touch inputs of the second pixelregion CA is less than the threshold value within the reference time.

In another embodiment, when the number of touch inputs of the secondpixel region CA is less than a threshold value or no touch input is madewithin the reference time, the drive IC 300 may lower the luminance of aspecific gray scale or greater in the second pixel region CA, in orderto reduce a difference in image quality perceived by a user and reducethe lifetime of pixels, considering the gray scale characteristics ofthe image displayed in the second pixel region CA.

The host system 200 may compare the touch frequency data of the secondpixel region CA with a preset threshold, and may output theregion-specific luminance control data (L-DATA) having an activationcode value for lowering luminance when the number of touch inputs of thesecond pixel region CA exceeds a threshold value within a referencetime, the second pixel region CA. In this case, the drive IC 300 lowersthe luminance of the second pixel region CA in response to the luminancecontrol data L-DATA having an activation code value.

The host system 200 may generate the region-specific luminance controldata L-DATA as a preset deactivation code value when the number of touchinputs of the second pixel region CA is less than a threshold valuewithin a reference time.

The host system 200 may transmit luminance control data L-DATA having anactivation code value to the drive IC 300 in order to lower theluminance of the second pixel region CA when an application in which atouch input of the second pixel region CA is frequently generated, forexample, a game application is executed. In addition, the host system200 may analyze the learning result of the AI processor and estimatewhether a touch input occurs frequently in the second pixel region CA,and transmit the luminance control data L-DATA having an activation codevalue to the drive IC 300 in order to lower the luminance of the secondpixel region CA when pixel data of an image having a high touch inputprobability of the second pixel region CA is output.

The drive IC 300 may equalize luminance of the first and second pixelregions DA and CA in response to the region-specific luminance controldata L-DATA having a deactivation code value.

In another embodiment, the drive IC 300 may lower the luminance of aspecific gray scale or greater in order to reduce a difference in imagequality perceived by a user and reduce the lifetime of pixels inresponse to the luminance control data L-DATGA having a deactivationcode value.

FIG. 12 is a diagram showing a luminance control device using digitalgamma compensation technology according to one embodiment. Thisluminance control device may be included in the data-calculating unit308 shown in FIG. 5 in one embodiment.

Referring to FIG. 12 , the luminance control device includes a luminancecontrol unit 3081 and a data conversion unit 3082.

The luminance control unit 3081 adjusts the luminance of the secondpixel region CA in response to the region-specific luminance controldata L-DATA. For example, the luminance control unit 3081 lowers theluminance of the second pixel region CA when it is determined that thefrequency of the touch input on the second pixel region CA is greaterthan or equal to the threshold value, or when it is determined as pixeldata of an image in which a touch input may occur in the second pixelregion.

The luminance control unit 3081 may be connected to a plurality oflook-up tables LUTs in which a gamma curve defining luminance for eachgray scale of the second pixel region CA is set. For example, in thefirst lookup table LUT1, a gamma curve defining luminance of the secondpixel region CA may be set with the same luminance as the first pixelregion DC for each gray scale. In the second lookup table LUT2, a gammacurve defining luminance of the second pixel region CA may be set tohave a luminance lower than that of the first pixel region DC in atleast some gray scales.

The luminance control unit 3081 selects a luminance value correspondingto the gray scale of the input pixel data from the first lookup tableLUT1 when the luminance of the second pixel region CA is controlled tothe same luminance as the first pixel region DA. The luminance controlunit 3081 selects a luminance value corresponding to the gray scale ofthe input pixel data from the second lookup table LUT2 when theluminance of the second pixel region CA is controlled to a lowerluminance than the first pixel region DA. The luminance control unit3081 may convert the luminance selected from the lookup tables LUT1 andLUT2 into a gray scale value, or convert it into a gray scale valueusing a luminance-gray scale conversion table to provide it to the dataconversion unit 3082.

The data conversion unit 3082 modulates the input pixel data into a grayscale value input from the luminance control unit 3081. The pixel dataDATA′ modulated by the data conversion unit 3082 is transmitted to thedata driver 305.

FIG. 13 is a diagram showing a luminance control device using analoggamma compensation technology according to one embodiment.

Referring to FIG. 13 , the data driver 305 includes a plurality of firstDACs DAC1 supplying a data voltage Vdata1 to pixels P1 of a first pixelregion DA, and a plurality of second DACs DAC2 supplying the datavoltage Vdata2 to the pixels P2 of the second DA.

The first DAC DAC1 converts the pixel data DATA to be written to thepixels of the first pixel region DA into a gamma compensation voltagefor each gray scale from a first gamma compensation voltage generatingunit PGAM1. A first data line DL1 connected to the first DAC DAC1 isconnected to the pixels P1 of the first pixel region DA. Accordingly,the data voltage Vdata1 output from the first DAC DAC1 is applied to thepixels P1 of the first pixel region DA through an output buffer and thedata line DL1.

The second DAC DAC2 converts the pixel data DATA to be written to thepixels P1 and P2 of the first and second pixel regions DA and CA togamma compensation voltage for each gray scale from a second gammacompensation voltage-generating unit PGAM2. The data line DL2 connectedto the second DAC DAC2 is connected to the pixels P1 of the first pixelregion DA and the pixels P2 of the second pixel region CA. Accordingly,the data voltage Vdata2 output from the second DAC DAC2 is applied tothe pixels P1 of the first pixel region DA and the pixels P2 of thesecond pixel region CA through the output buffer and the data line DL2.

The power supply unit 3050 illustrated in FIG. 2 includes a luminancecontrol unit 3051 and first and second gamma compensation voltagegenerating units PGMA1 and PGMA2.

Each of the first and second gamma compensation voltage generating unitsPGMA1 and PGMA2 is implemented as a programmable gamma compensationvoltage generating circuit. In the programmable gamma compensationvoltage generation circuit, the level of the output voltage may bevaried according to luminance data input from the luminance control unit3051.

The luminance control unit 3051 may output luminance data correspondingto the voltage defined in the gamma curve defining luminance of thefirst pixel region DA, and output luminance data corresponding to thevoltage defined in the gamma curve defining luminance of the secondpixel region CA. The luminance control unit 3051 may vary the luminancedata in response to region-specific luminance control data L-DATA tochange the voltage level of the gamma compensation voltage output fromthe DACs DAC1 and DAC2 for each region of the screen.

FIG. 14 is a diagram showing a gamma curve in which luminance is equallydefined in all regions of a screen according to one embodiment.

Referring to FIG. 14 , the luminance of the first and second pixelregions DA and CA may be equally controlled in order to increaseuniformity of luminance over the entire screen. Since the second pixelregion CA is a second pixel region, the data voltage may be generatedwith a higher voltage in order to obtain the same luminance as the firstpixel region DA.

In most cases, it is desirable to control the luminance of the secondpixel region CA equal to the luminance of the first pixel region DA tocontrol uniformly the image quality over the entire screen. However, ifthe data voltage is increased to make the luminance of the second pixelregion CA equal to the luminance of the first pixel region CA, since thepixels in the second pixel region CA receive more stress than the pixelsin the first pixel region CA, the deterioration may proceed faster andpower consumption may be increased.

The present disclosure improves pixel lifetime and power consumption ofthe second pixel region CA by lowering the luminance of the second pixelregion CA in a situation where the user does not feel sensitively evenif the luminance of the second pixel region CA is low.

The luminance control device may control the luminance of the secondpixel region CA to be lower than that of the first pixel region DA basedon at least one of the gamma curves shown in FIGS. 15 to 17 in order toextend the lifetime of pixels of the second pixel region CA and reducepower consumption.

FIGS. 15 to 17 are diagrams showing gamma curves in which luminance of ascreen is defined differently for each region according to oneembodiment.

Referring to FIG. 15 , the luminance of the second pixel region CA maybe lower than the luminance of the first pixel region CA at all grayscales except for gray scale 0 (zero). The gray scale 0 is a minimumgray scale value of the black luminance in which the light emittingelement is turned off.

Among an image displayed on the screen or an application screen, a touchinput generated on the second pixel region CA may be frequentlygenerated. An image currently reproduced on the learning result screenof the AI processor may be predicted as an image in which a touch inputof the second pixel region CA is frequently generated. When the mobileterminal rotates from vertical to horizontal, the second pixel region CAmay be covered by the user's finger by the user. An image whose imagequality is not important may be displayed on the second pixel region CA.For example, in a mobile terminal, a home button, an icon of a fixedapplication, a forward/backward button, and an option button are lesssensitive to luminance degradation. In such a situation, according tothe present disclosure, the luminance of the second pixel region CA maybe lowered, thereby extending the lifetime of pixels of the second pixelregion CA and lowering power consumption without deteriorating theperceived image quality of the user.

According to the present disclosure, the gray scale characteristics ofthe second pixel region CA may be determined by analyzing pixel data tobe written to the pixels of the second pixel region CA every frame. Inaddition, according to the present disclosure, the gray scalecharacteristics of the image reproduced on the screen are determined foreach frame period, such that the luminance of the second pixel region CAmay be controlled to be the same as that of the first pixel region DA ina gray scale less than a specific gray scale Hmax, as shown in FIGS. 16and 17 , while the luminance of the second pixel region CA may becontrolled to be lower than that of the first pixel region DA at aspecific gray scale Hmax or greater. Here, the specific gray scale Hmaxmay be varied according to the gray scale characteristics of the secondpixel region CA.

Referring to FIGS. 16 and 17 , the luminance of the second pixel regionCA is controlled equal to the luminance of the first pixel region CA ina gray scale less than a specific gray scale Hmax, and is controlled tobe lower than the luminance of the first pixel region DA in a gray scaleof a specific gray scale Hmax or greater.

In FIG. 16 , inclination of a gamma curve defining luminance of thesecond pixel region CA in a gray scale equal to or greater than aspecific gray scale Hmax is rolled off from the specific gray scaleHmax. In other words, as the inclination of the gamma curve is decreasedfrom the specific gray scale, the luminance of the second pixel regionCA may be increased to a low inclination as the gray scale or datavoltage increases.

In FIG. 17 , a gamma curve defining luminance of the second pixel regionCA in a gray scale equal to or greater than a specific gray scale Hmaxis saturated to the specific luminance. In other words, the luminance ofthe second pixel region CA may be fixed to a specific luminance in agray scale equal to or greater than the specific gray scale.

The luminance of the second pixel region CA may be adaptively selectedin FIG. 16 or 17 according to the analysis results of the gray scalecharacteristics of the input image.

FIG. 18 is a flowchart illustrating a method of controlling luminance ofa display device according to a first embodiment of the presentdisclosure. The various embodiments of the following luminance controlmethod may be implemented by the above-described display device, mobileterminal, and luminance control device.

Referring to FIG. 18 , the luminance control method may analyze an inputimage and determine whether a touch input of the second pixel region CAis frequently generated or an image is a predicted application image(S181 and S182). In this step, the AI processor may predict whether ornot an image in which a touch input may be frequently generated in thesecond pixel region CA. For example, in the case of a game, YouTube, orreal-time video streaming, the user may view the screen of the mobileterminal 2000 horizontally and hold both sides of the mobile terminalwith both hands as shown in FIG. 20 . In this case, the second pixelregion CA may be frequently touched by the finger or may be covered bythe finger.

In the luminance control method, when an image with little or no touchinput or an image predicted as such is input on the second pixel regionCA, the luminance of the second pixel region CA is controlled equal tothe luminance of the first pixel region DA (S182 and S183). In thiscase, the luminance control method may control luminance of the firstand second pixel regions DA and CA based on the gamma curve shown inFIG. 14 .

The luminance control method controls the luminance of the second pixelregion CA to be lower than the luminance of the first pixel region DAwhen a touch input is frequently generated on the second pixel region CAor an image of a predicted application is input (S182 and S184). In thiscase, the luminance control method may control the luminance of thesecond pixel region CA based on the gamma curve selected from FIGS. 15to 17 or control the luminance of the second pixel region CA byadaptively applying two or more gamma curves shown in FIGS. 15 to 17according to the gray scale characteristics of the input image. Forexample, the luminance control method may control luminance of thesecond pixel region CA based on the gamma curve shown in FIG. 16 , whenpixel data of a medium gray scale image with many medium gray scalepixel data (hereinafter referred to as “medium gray scale image”) isinput, in the pixel data to be written to the pixels of the second pixelregion CA. The luminance control method may control luminance of thesecond pixel region CA based on the gamma curve shown in FIG. 15 or 16 ,when pixel data of a low gray scale image with many low gray scale pixeldata (hereinafter referred to as “low gray scale image”) is input, inthe pixel data to be written to the pixels of the second pixel regionCA.

FIG. 19 is a flowchart illustrating a method of controlling luminance ofa display device according to a second embodiment of the presentdisclosure.

Referring to FIG. 19 , in the luminance control method, a touch input ofthe second pixel region CA is detected and the frequency is comparedwith a preset threshold Nth (S191 and S192).

The luminance control method controls the luminance of the second pixelregion CA equal to the luminance of the first pixel region DA when thefrequency of the touch input detected on the second pixel region CAwithin the reference time is less than the threshold value (S192 andS193). In this case, the luminance control method may control luminanceof the first and second pixel regions DA and CA based on the gamma curveshown in FIG. 14 .

In the luminance control method, as shown in FIG. 20 , when thefrequency of the touch input on the second pixel region CA within areference time is greater than or equal to the threshold value Nth, theluminance of the second pixel region CA is controlled to be lower thanthat of the first pixel region DA (S192 and S194). In this case, theluminance control method may control the luminance of the second pixelregion CA based on the gamma curve selected from FIGS. 15 to 17 orcontrol the luminance of the second pixel region CA adaptively applyingtwo or more gamma curves shown in FIGS. 15 to 17 according to the grayscale characteristics of the input image. For example, the luminancecontrol method may control luminance of the second pixel region CA basedon the gamma curve shown in FIG. 16 when the image to be displayed inthe second pixel region CA is a medium gray scale image. In theluminance control method, when the image to be displayed in thecurrently input second pixel region CA is pixel data of a low gray scaleimage, the luminance of the second pixel region CA may be controlledbased on the gamma curve shown in FIG. 15 or 17 .

FIG. 21 is a flowchart illustrating a method of controlling luminance ofa display device according to a third embodiment of the presentdisclosure.

Referring to FIG. 21 , the luminance control method senses movement andinclination of the mobile terminal 2000 in real time to determinewhether the mobile terminal 2000 is horizontally or vertically reversed(rotated by 180°) (S211 and S212).

In the luminance control method, when the mobile terminal 2000 is notrotated and the second pixel region CA is positioned at the top of thescreen, the luminance of the second pixel region CA is controlled in thesame manner as the luminance of the first pixel region DA(S211 andS213). If it is positioned at the top of the screen of the second pixelregion CA, the user may easily recognize the change in luminance of thesecond pixel region CA. Accordingly, when the mobile terminal 2000 doesnot rotate and the second pixel region CA is positioned at the top ofthe screen, the luminance of the second pixel region CA is controlled tobe the same as the luminance of the first pixel region DA.

In the luminance control method, as shown in FIG. 22 , when the mobileterminal 2000 is rotated horizontally, the second pixel region CApositioned on the top of the screen is touched or covered with a finger,and then when it is rotated by 180° and inverted vertically as shown inFIG. 23 , a home button that is not sensitive to image quality and anicon of a fixed application are displayed in the second pixel region CA.Therefore, in this case, the luminance control method controls theluminance of the second pixel region CA to be lower than that of thefirst pixel region DA (S212 and S214). In this case, the luminancecontrol method controls the luminance of the second pixel region CAbased on the gamma curve selected from FIGS. 15 to 17 or control theluminance of the second pixel region CA by adaptively applying two ormore gamma curves shown in FIGS. 15 to 17 according to the gray scalethe characteristics of the input image. For example, in the luminancecontrol method, when pixel data to be written to the pixels of thesecond pixel region CA that is currently input is a medium gray scaleimage, the luminance of the second pixel region CA may be controlledbased on the gamma curve shown in FIG. 16 . In the luminance controlmethod, when the pixel data to be written in the pixels of the secondpixel region CA that is currently input is the pixel data of the lowgray scale image, the luminance of the second pixel region CA maycontrolled based on the gamma curve shown in FIG. 15 or 17 .

Meanwhile, a UI screen such as a home button and a fixed applicationicon may be disposed in the second pixel region CA as shown in FIG. 23according to a user's setting.

FIG. 24 is a flowchart illustrating a method of controlling luminance ofa display device according to a fourth embodiment of the presentdisclosure. FIG. 25 is a diagram illustrating an example of a histogramshowing a gray scale characteristic of an input image.

Referring to FIGS. 24 and 25 , the luminance control method analyzesgray scale characteristics of the second pixel region CA (S241). As anexample, the luminance control method may determine gray scalecharacteristics of the second pixel region CA by accumulating pixel datato be written in pixels of the second pixel region CA for each grayscale during each frame period. FIG. 25A is an example of a low grayscale image in which the accumulated value of the low gray scale islarge in the histogram. FIG. 25B is an example of a medium gray scaleimage in which the accumulated values of the middle gray scale are largein the histogram. FIG. 25C is an example of a high gray scale image inwhich the accumulated value of the low gray scale is large in thehistogram.

In the luminance control method, when the image to be displayed in thesecond pixel region CA is the high gray scale image, the luminance ofthe second pixel region CA is controlled to be the same as the luminanceof the first pixel region DA (S242 and S243).

In the luminance control method, when the image to be displayed in thesecond pixel region CA is the low gray scale image, the luminance of thesecond pixel region CA is controlled to be lower than the luminance ofthe region DA in at least some gray scales based on the gamma curvesshown in FIGS. 15 to 17 (S244 to S247). In the luminance control method,the luminance of the second pixel region CA in a low gray scale imagemay be rolled off in a specific gray scale Hmax or greater to controlthe luminance lower than that of the first pixel region DA as shown inFIG. 16 (S244, S245). In the luminance control method, the luminance ofthe second pixel region CA in the low gray scale image is saturated in agray scale of a specific gray scale Hmax or greater, and fixed to aspecific luminance, such that the luminance may be controlled lower thanthat of the first pixel region DA (S246 and S247). The specific grayscale Hmax may be varied according to the gray scale characteristics ofthe input image.

The luminance control method illustrated in FIG. 24 may be applied whenthe number of touch inputs on the second pixel region CA is less than athreshold value, but is not limited thereto.

The objects to be achieved by the present disclosure, the means forachieving the objects, and effects of the present disclosure describedabove do not specify essential features of the claims, and thus, thescope of the claims is not limited to the disclosure of the presentdisclosure.

Although the embodiments of the present disclosure have been describedin more detail with reference to the accompanying drawings, the presentdisclosure is not limited thereto and may be embodied in many differentforms without departing from the technical concept of the presentdisclosure. Therefore, the embodiments disclosed in the presentdisclosure are provided for illustrative purposes only and are notintended to limit the technical concept of the present disclosure. Thescope of the technical concept of the present disclosure is not limitedthereto. Therefore, it should be understood that the above-describedembodiments are illustrative in all aspects and do not limit the presentdisclosure. The protective scope of the present disclosure should beconstrued based on the following claims, and all the technical conceptsin the equivalent scope thereof should be construed as falling withinthe scope of the present disclosure.

What is claimed is:
 1. A display device comprising: a display panel onwhich a pixel array including at least a first pixel region and a secondpixel region are disposed; a touch sensor on the pixel array; a displaypanel driver configured to write pixel data of an input image to pixelsfrom the pixel array that are in the first pixel region and the secondpixel region; a touch sensor driver configured to drive the touch sensorand detect a touch input on the pixel array to generate touch coordinatedata; and a luminance control device configured to control a luminanceof the first pixel region and a luminance of the second pixel region,wherein: the luminance control device is configured to lower theluminance of the first pixel region by rolling off the luminance of thesecond pixel region in a gray scale equal to or greater than a specificgray scale of a maximum frequency among gray scale values of pixel datato be written to the pixels of the second pixel region when the touchinput is detected on the second pixel region or, to fix the luminance ofthe second pixel region to a specific luminance that is less than theluminance of the first pixel region in a gray scale equal to or greaterthan a specific gray scale of a maximum frequency among gray scalevalues of pixel data to be written to the pixels of the second pixelregion when the touch input is detected on the second pixel region. 2.The display device of claim 1, wherein a pixels per inch (PPI) of thesecond pixel area is less than a PPI of the first pixel area.
 3. Thedisplay device of claim 1, wherein the luminance control device isconfigured to control the luminance of the second pixel region to beless than a luminance of the first pixel region responsive to a numberof touch inputs on the second pixel region being greater than or equalto a preset threshold within a predetermined reference time.
 4. Thedisplay device of claim 1, wherein the touch sensor driver is configuredto transmit luminance control data that controls the luminance of thesecond pixel region to the luminance control device.
 5. The displaydevice of claim 3, wherein the luminance control data includes frequencydata indicating a number of touch inputs generated on the second pixelregion, and touch coordinate data for the touch inputs in the secondpixel region.
 6. The display device of claim 3, wherein the displaypanel driver includes: a data driver configured to convert pixel data tobe written in the pixels of the second pixel region and the first pixelregion into a data voltage to supply the pixel data to the pixels, thedata driver and the luminance control device are mounted on a driveintegrated circuit (IC), a touch IC on which the touch sensor driver ismounted transmits the luminance control data to the drive IC, and thedrive IC includes a pin through which the luminance control data isreceived.
 7. The display device of claim 1, further comprising a hostsystem configured to transmit pixel data of an input image to thedisplay panel driver and receive the touch coordinate data from thetouch sensor driver, wherein the display panel driver includes: a datadriver configured to convert the pixel data to be written in pixels ofthe second pixel region and the first pixel region into a data voltageto supply the data to the pixels, the data driver and the luminancecontrol device are mounted on a drive integrated circuit (IC), the hostsystem transmits the luminance control data to the drive IC, and thedrive IC includes a pin through which the luminance control data isreceived.
 8. A method for controlling luminance of a display deviceincluding a display panel in which a pixel array including at least afirst pixel region and a second pixel region are disposed, and a touchsensor disposed on the pixel array, the method comprising: writing pixeldata of an input image to pixels from the pixel array that are in thefirst pixel region and the second pixel region; driving the touch sensorand detecting a touch input on the pixel array to generate touchcoordinate data; and lowering a luminance of one of the first pixelregion or a luminance of the second pixel region responsive to detectingthe touch input on the pixel array.
 9. The method of claim 8, wherein apixels per inch (PPI) of the second pixel area is less than a PPI of thefirst pixel area.
 10. The method of claim 8, wherein lowering theluminance of one of the first and second pixel regions responsive todetecting the touch input on the pixel array comprises: lowering theluminance of the second pixel region responsive to detecting the touchinput on the second pixel region.
 11. The method of claim 8, whereinlowering the luminance of one of the first pixel region or the secondpixel region responsive to detecting the touch input on the pixel arraycomprises: controlling the luminance of the second pixel region to beless than a luminance of the first pixel region responsive to a numberof touch inputs on the second pixel region being greater than or equalto a preset threshold within a predetermined reference time.
 12. Themethod of claim 8, wherein the lowering the luminance of one of thefirst pixel region or the second pixel region responsive to detectingthe touch input on the pixel array comprises: lowering the luminance ofthe first pixel region by rolling off the luminance of the second pixelregion in a gray scale equal to or greater than a specific gray scale ofa maximum frequency among gray scale values of pixel data to be writtento the pixels of the second pixel region.
 13. The method of claim 8,wherein lowering the luminance of one of the first and second pixelregions responsive to detecting the touch input on the pixel arraycomprises: fixing the luminance of the second pixel region to a specificluminance less than the luminance of the first pixel region in a grayscale equal to or greater than a specific gray scale of a maximumfrequency among gray scale values of pixel data to be written to thepixels of the second pixel region.
 14. A mobile terminal comprising: adisplay panel in which a pixel array including at least a first pixelregion and a second pixel region are disposed; a touch sensor disposedon the pixel array; a display panel driver configured to write pixeldata of an input image to pixels from the pixel array that are in thefirst pixel region and the second pixel region; a touch sensor driverconfigured to drive the touch sensor and detect a touch input on thepixel array to generate touch coordinate data; a sensor configured tosense changes in movement and inclination in real time; a host systemconnected to the sensor and configured to transmit the pixel data of theinput image to the display panel driver, and to receive the touchcoordinate data from the touch sensor driver; and a luminance controldevice configured to control a luminance the first pixel region and aluminance of the second pixel region, wherein the luminance controldevice is configured to lower the luminance of the second pixel regionresponsive to detecting the touch input on the second pixel region or,responsive to the mobile terminal being rotated or inverted.
 15. Themobile terminal of claim 13, wherein the luminance control device isconfigured to lower the luminance of the second pixel region responsiveto a number of touch inputs is greater than or equal to a presetthreshold within a predetermined time.
 16. The mobile terminal of claim13, wherein the luminance control device is configured to lower thesecond pixel region in a gray scale equal to or greater than a specificgray scale of a maximum frequency among gray scale values of pixel datato be written to pixels of the second pixel region.
 17. The mobileterminal of claim 13, wherein the second pixel region has a home buttonor icon displayed therein.